Doing an XM Skydock/iPod Touch in my 2007 Sport model. Signal strength is excellent when the antenna is placed flat on the bezel directly in front of the hood scoop screen--will affix antenna with 3M automotive tape since the bezel is non-magnetic plastic. Looks real clean in this location.

The issue now becomes, which is the best wiring bundle through point for routing the antenna lead through the firewall that's big enough to accommodate the antenna connector.

I was able to get the harness of an Emanage Ultimate (fuel computer) through the firewall of an IS300 and it's grommet is smaller than the one in the Tacoma. You should be able to get this done no problem. Use some Vaseline